This invention relates in general to rotary solenoid valves. Specifically, this invention is concerned with rotary solenoid valves particularly adapted for vehicular hydraulic systems such as brake and suspension systems.
Electronically controlled hydraulic brake systems for vehicles are well known. Such systems typically include a hydraulic control unit (HCU) connected between a master cylinder and wheel brakes. The master cylinder generates hydraulic forces in the brake circuit by pressurizing brake fluid when the driver steps on the brake pedal. The pressurized fluid travels through the fluid conduit in the circuit to actuate brake cylinders at the wheels and slow the vehicle.
The hydraulic control unit includes a housing mounting control valves and other components such as a pump. Through an electronic controller, the control valves and other components selectively control pressure to the wheel brakes to provide desired braking responses, such as anti-lock braking, traction control, and vehicle stability control.
Many of the control valves mounted in a HCU are formed as electronically controlled solenoid valves. A typical solenoid valve includes an armature that slides between two end positions in response to a magnetic flux generated by a coil subassembly of the solenoid valve. An armature can be formed as a cylindrical element slidably mounted in a tube or sleeve. Many electronically-controlled brake systems include both normally open solenoid valves (isolation valves) and normally closed solenoid valves (dump valves).
Electronically controlled hydraulic suspension systems include dampers shock absorbers and struts) and/or actuators. Such dampers and/or actuators typically include control valve that are opened and closed to permit fluid to selectively travel from a pressurized source of fluid. Many of the control valves used with dampers and actuators are electronically controlled solenoid valves.
It is desirable to manufacture economical control valves that provide desired responses in vehicular hydraulic systems. In many applications, it is desirable to provide control valves that are electronically controlled solenoid valves.